| |
| /* |
| * Copyright 2006 The Android Open Source Project |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| |
| #ifndef SkXfermode_DEFINED |
| #define SkXfermode_DEFINED |
| |
| #include "SkFlattenable.h" |
| #include "SkColor.h" |
| |
| class GrFragmentProcessor; |
| class GrTexture; |
| class GrXPFactory; |
| class SkString; |
| |
| /** \class SkXfermode |
| * |
| * SkXfermode is the base class for objects that are called to implement custom |
| * "transfer-modes" in the drawing pipeline. The static function Create(Modes) |
| * can be called to return an instance of any of the predefined subclasses as |
| * specified in the Modes enum. When an SkXfermode is assigned to an SkPaint, |
| * then objects drawn with that paint have the xfermode applied. |
| * |
| * All subclasses are required to be reentrant-safe : it must be legal to share |
| * the same instance between several threads. |
| */ |
| class SK_API SkXfermode : public SkFlattenable { |
| public: |
| SK_DECLARE_INST_COUNT(SkXfermode) |
| |
| virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count, |
| const SkAlpha aa[]) const; |
| virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count, |
| const SkAlpha aa[]) const; |
| virtual void xferA8(SkAlpha dst[], const SkPMColor src[], int count, |
| const SkAlpha aa[]) const; |
| |
| /** Enum of possible coefficients to describe some xfermodes |
| */ |
| enum Coeff { |
| kZero_Coeff, /** 0 */ |
| kOne_Coeff, /** 1 */ |
| kSC_Coeff, /** src color */ |
| kISC_Coeff, /** inverse src color (i.e. 1 - sc) */ |
| kDC_Coeff, /** dst color */ |
| kIDC_Coeff, /** inverse dst color (i.e. 1 - dc) */ |
| kSA_Coeff, /** src alpha */ |
| kISA_Coeff, /** inverse src alpha (i.e. 1 - sa) */ |
| kDA_Coeff, /** dst alpha */ |
| kIDA_Coeff, /** inverse dst alpha (i.e. 1 - da) */ |
| |
| kCoeffCount |
| }; |
| |
| /** List of predefined xfermodes. |
| The algebra for the modes uses the following symbols: |
| Sa, Sc - source alpha and color |
| Da, Dc - destination alpha and color (before compositing) |
| [a, c] - Resulting (alpha, color) values |
| For these equations, the colors are in premultiplied state. |
| If no xfermode is specified, kSrcOver is assumed. |
| The modes are ordered by those that can be expressed as a pair of Coeffs, followed by those |
| that aren't Coeffs but have separable r,g,b computations, and finally |
| those that are not separable. |
| */ |
| enum Mode { |
| kClear_Mode, //!< [0, 0] |
| kSrc_Mode, //!< [Sa, Sc] |
| kDst_Mode, //!< [Da, Dc] |
| kSrcOver_Mode, //!< [Sa + Da - Sa*Da, Rc = Sc + (1 - Sa)*Dc] |
| kDstOver_Mode, //!< [Sa + Da - Sa*Da, Rc = Dc + (1 - Da)*Sc] |
| kSrcIn_Mode, //!< [Sa * Da, Sc * Da] |
| kDstIn_Mode, //!< [Sa * Da, Sa * Dc] |
| kSrcOut_Mode, //!< [Sa * (1 - Da), Sc * (1 - Da)] |
| kDstOut_Mode, //!< [Da * (1 - Sa), Dc * (1 - Sa)] |
| kSrcATop_Mode, //!< [Da, Sc * Da + (1 - Sa) * Dc] |
| kDstATop_Mode, //!< [Sa, Sa * Dc + Sc * (1 - Da)] |
| kXor_Mode, //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + (1 - Sa) * Dc] |
| kPlus_Mode, //!< [Sa + Da, Sc + Dc] |
| kModulate_Mode, // multiplies all components (= alpha and color) |
| |
| // Following blend modes are defined in the CSS Compositing standard: |
| // https://dvcs.w3.org/hg/FXTF/rawfile/tip/compositing/index.html#blending |
| kScreen_Mode, |
| kLastCoeffMode = kScreen_Mode, |
| |
| kOverlay_Mode, |
| kDarken_Mode, |
| kLighten_Mode, |
| kColorDodge_Mode, |
| kColorBurn_Mode, |
| kHardLight_Mode, |
| kSoftLight_Mode, |
| kDifference_Mode, |
| kExclusion_Mode, |
| kMultiply_Mode, |
| kLastSeparableMode = kMultiply_Mode, |
| |
| kHue_Mode, |
| kSaturation_Mode, |
| kColor_Mode, |
| kLuminosity_Mode, |
| kLastMode = kLuminosity_Mode |
| }; |
| |
| /** |
| * Gets the name of the Mode as a string. |
| */ |
| static const char* ModeName(Mode); |
| |
| /** |
| * If the xfermode is one of the modes in the Mode enum, then asMode() |
| * returns true and sets (if not null) mode accordingly. Otherwise it |
| * returns false and ignores the mode parameter. |
| */ |
| virtual bool asMode(Mode* mode) const; |
| |
| /** |
| * The same as calling xfermode->asMode(mode), except that this also checks |
| * if the xfermode is NULL, and if so, treats it as kSrcOver_Mode. |
| */ |
| static bool AsMode(const SkXfermode*, Mode* mode); |
| |
| /** |
| * Returns true if the xfermode claims to be the specified Mode. This works |
| * correctly even if the xfermode is NULL (which equates to kSrcOver.) Thus |
| * you can say this without checking for a null... |
| * |
| * If (SkXfermode::IsMode(paint.getXfermode(), |
| * SkXfermode::kDstOver_Mode)) { |
| * ... |
| * } |
| */ |
| static bool IsMode(const SkXfermode* xfer, Mode mode); |
| |
| /** Return an SkXfermode object for the specified mode. |
| */ |
| static SkXfermode* Create(Mode mode); |
| |
| /** Return a function pointer to a routine that applies the specified |
| porter-duff transfer mode. |
| */ |
| static SkXfermodeProc GetProc(Mode mode); |
| |
| /** Return a function pointer to a routine that applies the specified |
| porter-duff transfer mode and srcColor to a 16bit device color. Note, |
| if the mode+srcColor might return a non-opaque color, then there is not |
| 16bit proc, and this will return NULL. |
| */ |
| static SkXfermodeProc16 GetProc16(Mode mode, SkColor srcColor); |
| |
| /** |
| * If the specified mode can be represented by a pair of Coeff, then return |
| * true and set (if not NULL) the corresponding coeffs. If the mode is |
| * not representable as a pair of Coeffs, return false and ignore the |
| * src and dst parameters. |
| */ |
| static bool ModeAsCoeff(Mode mode, Coeff* src, Coeff* dst); |
| |
| SK_ATTR_DEPRECATED("use AsMode(...)") |
| static bool IsMode(const SkXfermode* xfer, Mode* mode) { |
| return AsMode(xfer, mode); |
| } |
| |
| /** |
| * Returns whether or not the xfer mode can support treating coverage as alpha |
| */ |
| virtual bool supportsCoverageAsAlpha() const; |
| |
| /** |
| * The same as calling xfermode->supportsCoverageAsAlpha(), except that this also checks if |
| * the xfermode is NULL, and if so, treats it as kSrcOver_Mode. |
| */ |
| static bool SupportsCoverageAsAlpha(const SkXfermode* xfer); |
| |
| enum SrcColorOpacity { |
| // The src color is known to be opaque (alpha == 255) |
| kOpaque_SrcColorOpacity = 0, |
| // The src color is known to be fully transparent (color == 0) |
| kTransparentBlack_SrcColorOpacity = 1, |
| // The src alpha is known to be fully transparent (alpha == 0) |
| kTransparentAlpha_SrcColorOpacity = 2, |
| // The src color opacity is unknown |
| kUnknown_SrcColorOpacity = 3 |
| }; |
| |
| /** |
| * Returns whether or not the result of the draw with the xfer mode will be opaque or not. The |
| * input to this call is an enum describing known information about the opacity of the src color |
| * that will be given to the xfer mode. |
| */ |
| virtual bool isOpaque(SrcColorOpacity opacityType) const; |
| |
| /** |
| * The same as calling xfermode->isOpaque(...), except that this also checks if |
| * the xfermode is NULL, and if so, treats it as kSrcOver_Mode. |
| */ |
| static bool IsOpaque(const SkXfermode* xfer, SrcColorOpacity opacityType); |
| |
| /** Implemented by a subclass to support use as an image filter in the GPU backend. When used as |
| an image filter the xfer mode blends the source color against a background texture rather |
| than the destination. It is implemented as a fragment processor. This can be called with |
| both params set to NULL to query whether it would succeed. Otherwise, both params are |
| required. Upon success the function returns true and the caller owns a ref to the fragment |
| parameter. Upon failure false is returned and the processor param is not written to. |
| */ |
| virtual bool asFragmentProcessor(GrFragmentProcessor**, GrTexture* background) const; |
| |
| /** A subclass may implement this factory function to work with the GPU backend. It is legal |
| to call this with xpf NULL to simply test the return value. If xpf is non-NULL then the |
| xfermode may optionally allocate a factory to return to the caller as *xpf. The caller |
| will install it and own a ref to it. Since the xfermode may or may not assign *xpf, the |
| caller should set *xpf to NULL beforehand. XferProcessors cannot use a background texture. |
| */ |
| virtual bool asXPFactory(GrXPFactory** xpf) const; |
| |
| /** Returns true if the xfermode can be expressed as an xfer processor factory (xpFactory). |
| This helper calls the asXPFactory() virtual. If the xfermode is NULL, it is treated as |
| kSrcOver_Mode. It is legal to call this with xpf param NULL to simply test the return value. |
| */ |
| static bool AsXPFactory(SkXfermode*, GrXPFactory**); |
| |
| SK_TO_STRING_PUREVIRT() |
| SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP() |
| SK_DEFINE_FLATTENABLE_TYPE(SkXfermode) |
| |
| protected: |
| SkXfermode() {} |
| /** The default implementation of xfer32/xfer16/xferA8 in turn call this |
| method, 1 color at a time (upscaled to a SkPMColor). The default |
| implmentation of this method just returns dst. If performance is |
| important, your subclass should override xfer32/xfer16/xferA8 directly. |
| |
| This method will not be called directly by the client, so it need not |
| be implemented if your subclass has overridden xfer32/xfer16/xferA8 |
| */ |
| virtual SkPMColor xferColor(SkPMColor src, SkPMColor dst) const; |
| |
| private: |
| enum { |
| kModeCount = kLastMode + 1 |
| }; |
| |
| typedef SkFlattenable INHERITED; |
| }; |
| |
| #endif |
